Harmonic current detection method of double frequency phase lock based on cascade SOGI

The ip-iq harmonic detection method generated in the theory of instantaneous reactive power has a complicated structure and a relatively long delay time. In order to simplify the structure of harmonic detection and improve the accuracy and speed of detection, this paper proposed a double-frequency harmonic current detection method adopting cascade SOGI structure. In this paper, the calculation of the active and reactive components of the load current in the ip-iq harmonic detection method is omitted. Then, by combining two SOGIs into a cascade structure, the structure is then used to extract the fundamental wave in harmonic current detection. After that, the harmonic command current is obtained through mathematical operation, which provides a precondition for future harmonic compensation. The proposed method can detect harmonics accurately and quickly. Simulations verify the effectiveness and applicability of the proposed method.

I. Introduction

Due to the emergence of a large number of power electronic devices and the use of nonlinear loads, the harmonic pollution in the power system is becoming more and more serious. In order to solve various challenges and to ensure that renewable energy can be used stably in the grid through microgrids and smart grids [1]–[2], the adverse effects of harmonic pollution must be avoided. So far, a variety of harmonic detection methods have been proposed and applied to Active Power Filter (APF) to achieve the purpose of suppressing and compensating harmonics. To date, the commonly used harmonic detection methods include detection methods based on Fourier transform [3], detection methods based on instantaneous reactive power theory [4]–[5], detection methods based on neural networks, etc. For example, literature [6] uses the Prony algorithm combined with the improved Adaline model for harmonic detection and analysis, but this algorithm is more complicated to implement.